Optical device and method of making the same

Abstract

An optical device includes a first electrode of a first conductivity type, and a second electrode of a second conductivity type. A nanowire is positioned between the first and second electrodes. The nanowire has at least two segments and a junction region formed between the at least two segments. One of the segments is the first conductivity type and the other of the segments is the second conductivity type. At least one of the at least two segments has a predetermined characteristic that affects optical behavior of the junction region.

What is claimed is: 
     
       1. An optical device, comprising:
 a first electrode of a first conductivity type; 
 a second electrode of a second conductivity type; 
 a nanowire positioned laterally between the first and second electrodes, the nanowire having at least two segments and a junction region formed between the at least two segments, one of the at least two segments being one of grown from or attached to the first electrode and being of the first conductivity type, an other of the at least two segments being one of grown from or attached to the second electrode and being of the second conductivity type, and at least one of the at least two segments having a predetermined characteristic that affects optical behavior of the junction region; 
 a substrate upon which the first and second electrodes are established or from which the first and second electrodes are formed, the substrate having a surface that is substantially parallel to the nanowire and is positioned a spaced distance from the nanowire; and 
 a non-linear optical material covering the nanowire at least on the junction region. 
 
     
     
       2. The optical device as defined in  claim 1 , further comprising a reflective layer established on the substrate surface such that the entire reflective layer is positioned between the first and second electrodes, the reflective layer being a spaced distance from the nanowire. 
     
     
       3. The optical device as defined in  claim 2  wherein the reflective layer is selected from oxides, nitrides, oxynitrides, metals, semiconductors, and combinations thereof. 
     
     
       4. The optical device as defined in  claim 1 , further comprising electronics integrated i) in, ii) on, or ii) combinations of in and on the substrate. 
     
     
       5. The optical device as defined in  claim 1  wherein the non-linear optical material is selected from barium titanate, beta barium borate, bismuth germinate, cadmium zinc telluride, cesium lithium borate, lithium niobate, lithium tantalate, lithium triborate, monopotassium phosphate, neodymium doped yttrium aluminum borate, neodymium doped yttrium calcium oxyborate, nitrobenzene, potassium aluminum borate, potassium titanyl phosphate, tellurium dioxide, yttrium iron garnet, zinc telluride, or combinations thereof. 
     
     
       6. The optical device as defined in  claim 1 , further comprising electronics integrated on the substrate. 
     
     
       7. The optical device as defined in  claim 1  wherein the predetermined characteristic is selected from band gap, index of refraction, diameter, transmittance, absorbance, minority-carrier lifetime, band structure, radiative recombination ability, and combinations thereof. 
     
     
       8. The optical device as defined in  claim 1  wherein the first conductivity type is one of p-type and n-type, and wherein the second conductivity type is an other of n-type and p-type. 
     
     
       9. The optical device as defined in  claim 1  wherein each of the first and second electrodes has a growth initiating surface which is a surface of the respective electrode, and wherein the growth initiating surface of the respective electrode has a crystallographic orientation plane (111). 
     
     
       10. The optical device as defined in  claim 1  wherein the non-linear optical material covering the nanowire is spaced a distance from the substrate. 
     
     
       11. A method for using the optical device of  claim 2 , the method comprising:
 applying a voltage between the first and second electrodes, whereby electrons and holes recombine at or near the junction region, thereby emitting light; 
 reflecting at least a portion of the emitted light via the reflective layer; and 
 collecting the reflected light. 
 
     
     
       12. A method for using the optical device of  claim 1 , the method comprising:
 applying a voltage between the first and second electrodes, whereby electrons and holes recombine at or near the junction region, thereby emitting light of a first wavelength; 
 absorbing, via the non-linear optical material, the light of the first wavelength; and 
 emitting, from the non-linear optical material, light of a second wavelength. 
 
     
     
       13. The method as defined in  claim 12  wherein the light of the second wavelength is shorter or longer than the light of the first wavelength. 
     
     
       14. A method for making an optical device, comprising:
 selecting, for at least one of a first nanowire segment or a second nanowire segment, at least one predetermined characteristic that affects optical behavior of a junction region formed between the first and second nanowire segments; 
 laterally growing the first nanowire segment of a first conductivity type from a first electrode of the first conductivity type; 
 laterally growing the second nanowire segment of a second conductivity type from the first nanowire segment such that the second nanowire segment attaches to a second electrode having the second conductivity type; 
 establishing or forming the first and second electrodes on a silicon substrate, the silicon substrate having a surface that is substantially parallel to and positioned a spaced distance from the first and second nanowire segments; and 
 covering at least the junction region of the nanowire with a non-linear optical material; 
 whereby at least one of the first and second nanowire segments includes the at least one predetermined characteristic. 
 
     
     
       15. The method as defined in  claim 14  wherein the predetermined characteristic is selected from band gap, index of refraction, diameter, transmittance, absorbance, minority-carrier lifetime, band structure, radiative recombination ability, and combinations thereof. 
     
     
       16. The method as defined in  claim 14 , further comprising integrating electronics i) in, ii) on, or ii) combinations of in and on the silicon substrate. 
     
     
       17. The method as defined in  claim 14 , further comprising establishing a reflective layer on the substrate surface such that the entire reflective layer is positioned between the first and second electrodes. 
     
     
       18. An optical system, comprising:
 a substrate; 
 electronics integrated i) in, ii) on, or ii) combinations of in and on the substrate; and 
 at least one light-emitting diode established on the substrate and in electrical communication with the integrated electronics, the light-emitting diode including:
 first and second electrodes, wherein the first electrode is of a first conductivity type, and the second electrode is of a second conductivity type; 
 a nanowire laterally positioned between the first and second electrodes, the nanowire having at least two segments and a junction region formed between the at least two segments, one of the at least two segments one of grown from or attached to the first electrode and having the first conductivity type, an other of the at least two segments one of grown from or attached to the second electrode and having the second conductivity type, and at least one of the at least two segments having a predetermined characteristic that affects optical behavior of the junction region; and 
 a non-linear optical material covering the nanowire at least on the junction region; 
 
 wherein the substrate has a surface that is substantially parallel to and spaced from the nanowire. 
 
     
     
       19. The optical system as defined in  claim 18 , further comprising a reflective layer established on a surface of the substrate and positioned between the first and second electrodes, the reflective layer being substantially parallel to and a spaced distance from the nanowire.